A study from Umea University in Sweden has found that half of the 400 women who participated in their overnight sleep tests have mild-to-severe sleep apnea, a condition that until now was mostly associated with men. It's defined by the subject not breathing for longer than 10 seconds during sleep, and the study classified that five or more of these 10-second periods indicated mild to severe sleep apnea. There is a concurrent drop in blood oxygen levels, and the severe form of the condition is tied to stroke, heart attack and premature death. Last month, a study also tied it to memory problems and dementia.

"The prejudice of excluding women (as potentially having sleep apnea) has been rampant for a long time. It's gotten better, however, and the (public health) gain in identifying women with sleep apnea is great," said Terry Young, a public health professor and researcher at the University of Wisconsin.

The majority of the 200 had the "mild" form of the condition, but Young says that even this should be monitored to see if it escalates. Women studied who were obese or had hypertension were 80-84% likely to have sleep apnea, and numbers also escalated in older women.